High capacity submerged hot gas heat exchanger



Feb. 13, 1968 J. J. SANTOLERI ETAL 3,368,548

HIGH CAPACITY SUBMERGED HOTGAS HEAT EXCHANGER Filed Feb. 24, 1966 4 Sheets-Sheet 1 INVENTORS. JOSEPH J. SANTOLER! J AMES E. RICHARDSON ATrYs,

HIGH CAPACITY SUBMERGED HOT GAS HEAT EXCHANGER Filed Feb. 24, 1966 J. J. SANTOLERI ETAL Feb. 13, 1968 4 Sheets-Sheet 2 v mvzm'ons. JOSEPH J. SANTOLERI JAMES E. RICHARDSON v I ATT vs.

HIGH CAPACITY SUBMERGED HOT GAS HEAT EXCHANGER Filed Feb. 24, 1966 Feb. 13, 1968 J. J. SANTOLERI ETAL 4 Shets-Sheet rl k) INVENTORS; JOSEPH J. SANTOLERI JAMES E. RICHARDSON' .AT S- Feb. 13, 1968 J. J. SANTOLERI ETAL 3,368,548

I HIGH CAPACITY SUBMERGED HOT GAS HEAT EXCHANGER Filed Feb; 24, 1966 4 Sheets-Shet 4 11:1 iiiiiijiiiij; l r

' INVENTORSZ JOSEPH J. SANTOLERI JAMES ERICHARDSON mm W United States Patent 3,368,548 HIGH CAPACITY SUBMERGED HOT GAS HEAT EXCHANGER Joseph J. Santoleri, Wayne, and James E. Richardson,

Norristown, Pa., assignors to Thermal Research & Engineering Corporation, Conshohocken, Pa., a corporation of Delaware Filed Feb. 24, 1966, Ser. No. 529,786 Claims. (Cl. 126-360) ABSTRACT OF THE DISCLOSURE A submerged hot gas heat exchanger for heating extremely cold liquid such as nitrogen to change its state from the liquid state to the gaseous state. The hot gas heat exchangerincludes a tank containing a heat transfer liquid, a plurality of burners surrounded by a shroud depending downwardly into the tank, a weir surrounding the shroud to direct hot gas from the burner outwardly at the bottom of the tank into the liquid contained within the tank and a plurality of tubes within the tank outside of the weir through which the liquid to be heated and converted to the gaseous state is caused to pass.

The present invention relates to submerged hot gas heat exchangers and more particularly to the apparatus necessary for construction of a high capacity hot gas heat exchanger.

The submerged hot gas heat exchanger of the present invention comprises a tank of any desirable configuration for holding a quantity of heat exchange liquid and a plurality of elements which nest interiorly of the tank. The elements comprise a support framework which is positioned within the tank and supported by the bottom wall of the tank. The framework supports a weir having a lower terminus spaced from the bottom wall of the tank. Mounted in the weir is a shroud having a continuous depending closed wall supported by support means which are connected to the framework. The shroud preferably terminates at its lower end above the lower terminal end of the wall of the weir, and a bafiie is provided partially covering the lower end of the shroud and providing a series of apertures at the lower end of the shroud. A plurality of burners are provided to discharge hot products of combustion at a high velocity downwardly into the shroud and out through the aforementioned apertures into the space between the shroud and weir. Intermediate the shroud and the weir are process fluid inlet and outlet headers connected by a serpentine tube nest.

The principle of the operation of the present invention is best disclosed in the Hyer et al. Patent Number 3,138,- 150. The Hyer patent relates to a submerged hot gas heat exchanger especially advantageous for heating extremely cold liquids, such as nitrogen, to change its state from a liquid to a gas. Although the Hyer apparatus is of relatively high capacity for the size of the unit, an increased capacity unit may be desirable in times of high demand. The structural problems of supporting an increased size tank having a plurality of burners or one large burner involves difiiculties not heretofore encountered in the smaller Hyer device.

In designing a high capacity heat exchange unit of the Hyer type, it is conceded that a large single burner having an increased combustion capacity would permit an increase in the heat exchange capacity of the unit. However, it hasvbeen discovered that a large burner requires such an increase in the downcomer or shroud length that the design becomes unfeasible. This is because as the 3,368,548 Patented Feb. 13, 1968 "Ice length of the downcomer increases an increased water level is required in the tank to keep the downcomer tube cool while requiring an increase in the hot gas pressure necessary to offset the increased water level in the tank.

In view of the above, it is a principal object of the present invention to provide a high capacity submerged hot gas heat exchanger embodying the heat exchange principles of the Hyer device but of a new and inventive structure.

Another object of the present invention is to provide a novel heat exchange structure based on the Hyer principle while effecting an overall reduction in the size of tank necessary as opposed to a single, large burner type device having the same capacity.

Still another object of the present invention is to provide a high capacity submerged hot gas heat exchanger having a reduced vertical downcomer or shroud length while maintaining the overall efficiency of the single burner unit.

Still another object of the present invention is to provide a high capacity submerged hot gas heat exchanger of a multiple burner design which will permit the compacting of the structure into a smaller plot area as well as a decrease in elevation of the entire unit.

Other objects and a fuller understanding of the invention may be had by referring to the following specification and claims taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagrammatic, perspective, exploded view of a submerged hot gas heat exchanger constructed in accordance with the present invention;

FIG. 2 is a fragmentary side elevational view illustrating the apparatus of FIG. 1 in its nested position;

FIG. 3 is a plan view of the apparatus illustrated in FIG. 2 and as if FIG. 2 were not in section;

FIG. 4 is a fragmentary enlarged sectional view taken along line 44 of FIG. 2; and

FIG. 5 is a fragmentary sectional view taken along line 55 of FIG. 4.

Referring now to the drawings and especially FIG. 1 thereof, a heat exchanger comprising a tank 10 of any desirable configuration, in the illustrated instance rectangular, is adapted to hold a quantity of heat exchange liquid such as water and a plurality of elements nested interiorly of the tank. The tank may be positioned either exteriorly of the ground on supporting legs 11 or a suit- .ably walled and floored tank may 'be positioned in the ground.

In accordance with the invention, positioned interiorly of the tank for support by the bottom wall of the tank is a support frame 20 having uprights 21 including channels or angle members, and a circumscribing upper frame work 22 connected to the uprights 21. Interiorly of the support frame 20 is a weir 24 having circumferential, continuous and depending side walls 25. The weir also includes a sill or upper terminal edge 27 and a lower terminal edge 26 spaced from the lower terminal portion of the uprights 21 and thus the bottom wall of the tank to provide fluid communication between the tank and the weir. Mounted within the weir 24 is a shroud 40 having depending, continuous side walls 41 and upper support means 42 including longitudinal and transverse bracing 43 and 44 secured to and supported by the framework 22 of the support frame 20.

As illustrated in FIGS. 4 and 5, carried by the shroud is a plurality of downwardly projecting burners 50, in the present instance three aligned longitudinally of the shroud, for discharging hot products of combustion downwardly into the shroud and outwardly from the shroud through a plurality of apertures 45, opening radially outward adjacent the lower terminal portion of the shroud 40. The side walls 41 of the shroud are preferably connected at the lower terminal endsthereof by a baflle or the like 46 to aid in directing the gas flow outwardly from the apertures 45. The vertical position of the apertures 45 in the side walls 41 f the shroud, when the support means 42 is carried by the framework 22, is such as to be above the lower terminal edge 26 of the weir 24. In addition, mounted interiorly of the weir 25, intermediate the weir, is a process fluid inlet header 30 and a gaseous outlet header 32 connected by means of a serpentine tube nest 31.

From the foregoing it is understood that the support frame 20 mounted interiorly of the tank supports the entire structural weight of the weir, shroud and tube nestheader combination. The only necessity of the tank construction being that the bottom wall be capable of carrying the support frame and the upstanding walls of the tank have sutficient structural strength to hold a quantity of heat exchange liquid such as water therein.

In order to provide hot gas flow downwardly and out through the apertures 45 of the shroud 40, each of the burners 50 have air inlet piping 51 connected to a common header 52 to supply air to the burners 50, and a fuel inlet 53 connected to a common fuel manifold 54. Thus, ignition takes place within the burners and is directed downwardly into the shroud with suflicient pressure and velocity to substantially empty the shroud of any heat exchange liquid contained therein.

As illustrated in FIG. 5, the products of combustion or hot gas emanating from the apertures 45 pass upwardly in the form of bubbles across the tube nests 31, on either side of the shroud and between the shroud and weir 24. As best illustrated in FIGS. 4 and 5, the tube nests 31 are preferably supported by hangers 33 having projections, in the present instance transverse rods 34, upon which the tubes rest, the rods 34 being welded to a pair of hangers 33. As illustrated in FIG. 4, the rods 34 support spacers 34a located intermediate the longitudinal runs of the tubes to separate the same and permit maximum conduction with the surrounding bath. In the present instance the hangers are preferably connected to the transverse bracing 44 associated with the shroud support means 42.

As the hot gas heat exchanger is particularly applicable for heating cryogenic materials, such as liquid nitrogen, methane, propane, natural gas, hydrogen, oxygen, and ammonia, etc., having varying low temperatures, i.e., from minus 28 F in the instance of liquid ammonia to minus 420 F., for liquid hydrogen, it is preferable that the fluid inlet header lie closely adjacent the apertures 45 in the shroud 40 and that means be provided for permitting expansion and contraction of this header under these varying temperature conditionsv To this end, and as best illustrated in FIG. 2, the fluid inlet header 30 is supported by pipe expansion rollers 35 which in turn are connected to adjacent uprights 21, thus allowing expansion and contraction of the inlet header 30. In addition, as best shown in FIG. 5, the header 30 is located adjacent some of the apertures 45 in one of the side walls of the shroud which helps prevent the build-up of ice or the like around the fluid inlet header 30. Prevention of ice build-up is due to the agitation of the gas impinging upon the header in the form of bubbles formed in the heat exchange fluid. In a like manner the gas outlet header 32 is supported by a pipe hanger 36 or the like connected directly to the uprights 21 or the framework 22, as desired.

Although the temperature of the gas leaving the outlet or gas header 32 may vary depending upon such factors as ambient temperatures, initial heat exchange liquid temperature, the liquid entering the fluid inlet header 30, the combustion rate of the burners 50 and the type of fuel and fuel/ air mixture as well as rate of combustion, it has been found that an outlet temperature of approximately 40 F., is desirable and typical. Thus, in operation the hot gases are directed via the shroud to a point under the liquid level whereby the gases discharge directly into the heat exchange liquid 'bath. The high velocity combustion coupled with direct contact creates an extremely high heat transfer area in the form of gas bubbles and turbulent heat exchange liquid which results in extremely rapid heat transfer. In addition, the highly turbulent motion imparted to the heat exchange liquid creates turbulence which in conjunction with the normal tendency of the gas to rise tends to circulate the heat exchange liquid under the tube nest 31 at high velocities.'As illustrated in FIGS. 2, 4 and 5, this permits the liquid between the weir and the shroud to rise up over the sill or edge 27 of the weir and fall down into the surrounding bath intermediate the weir and the periphery of the tank 10, the heat exchange liquid supply being replenished via the material channel beneath the lower terminal edge 26 of the weir communicating with the surrounding bath.

In order to provide an outlet for the products of combustion escaping the tube nest 31 and over the sill 27 of the weir '24, a stack 55 is positioned intermediate the periphery of the tank and the support frame 20.

To minimize heat loss and to permit access to the interior of the tank in the event servicing or cleaning of the tank and/ or its nested elements is necessary, a segmented cover 60 (see FIG. 1) is provided which fits around the projecting stack, burners and piping.

In a like manner, to allow for filling and drainage of the tank in the event cleaning becomes desirable, fill pipes 12 are provided on either side of the tank for supplying heat exchange liquid both for make-up purposes and for refilling purposes, and a bottom drain line 13 having a drain valve 14 therein is included.

Thus, the present invention provides a high capacity hot gas heat exchanger of the Hyer type which heat exchanger is of multiple burner design and permits the compacting of the structure into a small plot area as well as a lower elevation while maintaining its high capacity output. In addition, due to the structure of the device, ready assembly and access to the interior is permitted.

Although the invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by Way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be made without departing from the spirit and the scope of the invention as hereinafter claimed.

We claim:

1. A submerged hot gas heat exchanger comprising: a tank having a bottom wall and upstanding side walls for holding a quantity of heat exchange liquid, and means to supply liquid thereto, a weir position interiorly of said tank, said weir including a wall portion having a lower terminus spaced from the bottom of said tank; a support frame interiorly of said tank supported by the bottom wall thereof and supporting said weir, a shroud mounted in said weir having a continuous closed Wall, support means connecting said shroud to said support frame, a baflle at the lower terminal portion of said shroud wall and a plurality of apertures opening radially at a point above the lower terminal end of said shroud wall and above said lower terminus of said wall of said weir, a plurality of fuel burners carried by said support means, each burner having a nozzle facing downwardly into said shroud, said burners having sufficient combustion velocity when said exchanger is in operation, to move heat exchange liquid out of said shroud through said apertures, a process fluid inlet header and outlet gas header positioned in said weir and above the lower terminal end thereof, at least one serpentine tube nest connecting said headers and mounted in said weir intermediate said weir and said shroud.

2. A hot gas heat exchanger in accordance with claim 1 wherein said process fluid inlet header lies closely adjacent at least some of said apertures.

3. A hot gas heat exchanger in accordance with claim 1 including a plurality of panels covering the top of said tank.

3,368,548 n n 6 4. A hot gas heat exchanger 1n accordance wrth clalm References Cited 1 including an expansion roller underlying said fluid inlet header and connected to said framework. UNITED TATES ATENTS 5. A hot gas heat exchanger in accordance With claim 3,138,150 6/1964 Hyer t a1 126 360 1 wherein said support means includes longitudinal and 5 3,187,743 6/1965 Primas 126-36 X transverse braces, depending tube support hangers con- 3,209 745 10/1965 Gl e t a1, 126 360 X nected to at least one of said braces and including projections thereon for supporting said tube nest. KENNETH W. SPRAGUE, Primary Examiner. 

